Hi, I'm buying a used set of Sound Dynamic speakers... The owner doesn't know what model they are and apparently the label is missing... they appear to be RTS 7's but I'm not sure from the photo if the have a trapezoidal cab. The speaker configuaration appears identical but the cab may be square... is there a set of sound dynamics that better match that descripion... please see photo and tell me if you believe these to be rts7's. I would love to have the manual for whatever speakers these are to better understand what I'm buying. Thanks, Mike